By Yayat Supriatna and Michael Taylor
JAKARTA Jan 11 (Reuters) - U.S. mining giant Freeport McMoRan Copper and Gold Inc halted its copper exports from Indonesia, less than an hour before a controversial mineral export ban comes into effect, a union official told Reuters late Saturday.
Indonesia on Sunday will impose a ban on more than $10 billion worth of annual copper, nickel and other unprocessed mineral ore shipments, a move that industry officials warn could lead to mass layoffs, mine closures and depleted foreign revenue.
The Southeast Asian nation is the world's biggest exporter of nickel ore, refined tin and thermal coal and home to the fifth largest copper mine and top gold mine.
The ban aims to boost Indonesia's long-term return from its mineral wealth, but officials fear a short-term cut in foreign revenue could widen the current account deficit, which has undermined investor confidence and battered the rupiah.
President Susilo Bambang Yudhoyono and cabinet ministers met late into the evening on Saturday to discuss whether to approve last-minute regulations that would ease the ban.
"There will be no concentrate exports from Freeport Indonesia in Papua as long as there is no government policy providing certainty on concentrate exports," said union official Virgo Solossa, adding that the firm has not made a shipment from its port since Dec. 15.
Company spokeswoman Daisy Primayanti said Freeport continued to ship copper to its local smelter for use domestically.
"We hope the government will issue the new implementing regulations soon," she said.
Freeport, the country's dominant copper produce with 73 percent market share, last month warned an unrevised ban would cut output at its Grasberg mine by 60 percent and lead to layoffs of half of its 15,000 Indonesian employees.
Indonesian miner Perusahaan Perseroan Aneka Tambang (Antam) has also stopped its nickel ore exports due to the ban, said the firm's corporate secretary Tri Hartono.
Under the proposal being reviewed by the president, Freeport, Newmont Mining Corp and other miners would still be allowed to export copper, manganese, lead, zinc and iron ore concentrate until 2017. But nickel ore and bauxite exports worth more than $2 billion annually would still be banned from Sunday, while coal and tin shipments would not be affected.
Thousands of mine workers have already been laid off as more than 100 junior miners halt operations ahead of the ban.
"We call on all mining workers to prepare to go on the streets and swarm the presidential palace if the government goes ahead with the implementation of the ban," said Juan Forti Silalahi of the National Mine Workers Union in a statement earlier on Saturday.